Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Avalanche problems should transition from wet to dry as you ascend in elevation on Friday as a quick shot of precipitation impacts the zone. Stay out from under steep rocky slopes that can shed snow down on top of you and avoid wind-drifted piles of snow.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Observations from Snoqualmie Pass indicate that there are around 3 inches (8cm) of low-density snow sitting on top of the rain crust that was formed by this week’s atmospheric river event. On the tail end of that event, winds were certainly strong enough to transport this snow or any cold and dry snow above the rain/snow line onto leeward slopes or toward the sides of gullies and bases of cliffs to form Wind Slabs. With a quick shot of precipitation in the forecast for Thursday night and Friday morning, middle and upper elevations may get a few more inches on top of the existing snow. The rain/snow line from the previous event still has not been confirmed, and it may be that rain was able to reach the ridgelines and peaks around the zone. If this is the case, you may only be dealing with slabs created by the wind drifting the previous 3” plus any new snow that falls. The current surface snow is weak, so if it gets buried, these slabs could be reactive. Use the previous rain crust as an indicator to help you identify if you are looking for new or old Wind Slabs. If you find the crust a few inches below the surface, you will be dealing with new Wind Slabs. If you are plunging into deeper snow, then be on the lookout for larger slabs involving this past week’s snow. In either scenario, keep an eye out for wind-textured snow surfaces or smooth pillow-like piles of snow to help you identify wind-loaded features to steer around.

    (1/13/2021) Look for wind drifted snow at the base of cliffs, on leeward slopes, or the sides of gullies. [Photo: Charlie Hagedorn]

  • Glide Cracks

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    We just wrapped up a significant wet avalanche cycle, and it looks like we may get a bit more rain at low to mid elevations on Thursday night into Friday morning. The snowpack at these elevations is pretty beat up at this point, but multiple glide cracks have been observed in the zone, and throwing a little more water into them may be all that’s needed to tip the scales for these slopes. Glide cracks may look like crevasses and are often found on steep, smooth rocky slopes. If you notice one of these, give it a wide berth by not traveling underneath it.

    With a little bit of snow sitting atop a crust at all elevations, we should also mention that the rain could cause some Wet Loose activity tomorrow. Slides should be small since there is not a lot of snow available, but don’t let one catch you in consequential terrain. If you find rain falling on dry snow, see fresh rollerballs, pinwheels, or fan-shaped avalanche debris, head for lower angled terrain away from steep slopes above you.

    (1/13/2021) This Glide avalanche occurred at Alpental on a slope that is known for these types of slides. On the right side of the picture, you can see a Glide Crack on a slope that has not yet climaxed. [Photo: Charlie Hagedorn]

Avalanche Discussion

Taking a look around Snoqualmie Pass on Thursday, evidence of this past week’s avalanche cycle is everywhere you look, with crowns on most features and plenty of avalanche debris. We should have that cycle pretty much wrapped up at this point aside from the possibility of a Glide avalanche being triggered by additional rain on Friday morning. With some new precipitation and freezing levels around 5500’, we will again be dealing with wet problems below the rain/snow line and dry snow problems above. We expect any avalanche activity to occur above the recent crust, with the exception of a Glide avalanche, which could be large and deadly. 

More concerning could be the travel conditions out there. Although better than originally anticipated, creeks are swollen, trees have broken, and there is a lot of avalanche debris on slopes. Travel cautiously and think about the consequences of a slip and fall.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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